A scanning probe microscope (SPM: Scanning Probe Microscopy) is an apparatus configured to measure and map the surface structure and physical properties of a measurement sample. Depending on the physical properties to be measured, various scanning probe microscopes have been developed, such as scanning tunneling microscopes (STM: Scanning Tunneling Microscope) and atomic force microscopes (AFM). In particular, a scanning Hall probe microscope (SHPM: Scanning Hall Probe Microscopy) is a measuring apparatus that is useful for quantitatively and directly observing magnetic domains; the scanning Hall probe microscope is configured to detect leakage magnetic fields from a magnetic material or a magnetic medium and to measure the physical quantity distribution of magnetic properties of the leaking magnetic fields and display the distribution as an image. Known scanning probe microscopes are described in, for example, Non-Patent Document 1 and Patent Document 1.    [Non-Patent Document 1] “Real-time scanning Hall probe microscopy,” Appl. Phys. Lett, 69, pp. 1324-1326, (1996)    [Patent Document 1] Japanese Patent Laid-Open No. 2004-226292
The conventional scanning Hall probe microscope described in Non-Patent Document 1 uses a Hall probe including an STM chip and a Hall element integrated together to perform magnetic imaging measurement. The Hall probe is fixed to the leading end of a tube-like piezoelectric (PZT) actuator. The Hall probe is kept in proximity to the surface of a measurement sample until a tunnel current starts to flow between the STM chip and the measurement sample. A feedback circuit in the Hall probe monitors the tunnel current. Thus, the Hall probe kept at a given distance from the measurement sample (lift mode) scans the surface of the measurement sample.
However, the measurement using the Hall probe with the STM chip as described above is limited to measurement samples with conductive surfaces. Furthermore, a complicated electronic circuit is required to monitor the tunnel current. Moreover, since the Hall probe is separated from the surface of the measurement sample, it is difficult to achieve measurement at a sufficiently high sensitivity and a sufficiently high spatial resolution using weaker magnetism. Additionally, the Hall probe fixed to the piezoelectric actuator floats at a short distance (for example, several nm) from the surface of the measurement sample. Thus, upon undergoing a certain external impact during measurement, the Hall probe may come into contact (interfere) with the measurement sample. As a result, one or both of the Hall probe and the measurement sample may be damaged accidentally or over time.
Furthermore, the Hall probe is swung along the surface of the measurement sample using the portion thereof fixed to the piezoelectric actuator as a support point, to subject the surface of the measurement sample to fine (micromotion) scanning. Thus, a gradual increase in swing angle progressively increases the distance between the Hall probe and the measurement sample. This reduces the resolution of measurement images in the scanning direction, making the images blurred. Moreover, a high voltage required to control the piezoelectric actuator may induce spurious noise and the like.
Moreover, to allow the vortex state of a superconductive material or the like to be observed, the measurement sample and the Hall probe need to be cooled to a liquid helium temperature. However, the tube-like piezoelectric actuator offers a very narrow displacement range at such very low temperature, thus limiting the scan range of the Hall probe to about 1 μm×1 μm. This prevents the measurement sample from being observed over a wide range. To solve this problem, the present inventors have proposed a configuration in which the piezoelectric element described in Patent Document 1 is installed in a room temperature environment. The present inventors have thus successfully applied the scanning Hall probe microscope to very low temperature. However, this apparatus has a slightly complicated configuration and requires an increased installation area for the members thereof. Thus, there has been a demand for a further reduction in the scale of the apparatus.